How in the flying fuck is forcefully sodomizing someone not rape? What the hell was the author thinking when they wrote this sentence?
Just a few guesses...
1) Most people think of "rape" as "penis/vagina" contact. (Or at least, contact of some part of the body, like a finger, with the vagina.) To differentiate the first action from the penis-vagina rape, the author used two different terms. Also, phrasing it that way allows the author to say that the officer did more than vaginally rape the victim. (If the author just said "the officer raped her," the reader is not aware of the other actions he took.)
2) Use of euphemisms. The author didn't want to say "the officer forced her to perform oral sex on him" or the like. It's wordy and (since I can't think of another way to phrase it) makes people picture what he did. So the author writes that the officer sodomized her, which gets the point across without sounding "crude."